JPH04202627A - Method for irradiating electron beam - Google Patents

Abstract

PURPOSE:To obtain a grain-oriented silicon steel sheet free from the deterioration of iron loss even if stress relieving annealing is executed and having a good shape, in the method for manufacturing a grain-oriented silicon steel sheet low in iron loss, by specifying the method for irradiating electron beams. CONSTITUTION:The entire length on the surface of a grain-oriented silicon steel sheet provided with an insulating coating film essentially consisting of phosphate and colloidal silica and subjected to finish annealing is irradiated with electron beams. At this time, the positions equal to the surface and back faces of the above steel sheet are repeatedly irradiated with electron beams having the same scanning directions. By this method, because iron loss is not deteriorated even if stress relieving annealing is executed, the need of strengthening the electron beams to be irradiated and narrowing the scanning distance is eliminated, the shape of the silicon steel sheet is not deteriorated.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an electron beam irradiation method useful for manufacturing unidirectional silicon steel sheets with low core loss, and in particular to subdivision of magnetic domains of the silicon steel sheets. The aim is to further reduce iron loss.

(Prior technology) Unidirectional silicon steel sheets are made by highly accumulating secondary recrystallized grains in the Goss orientation, and a forsterite film is formed on the surface of the steel sheet, and an insulating film with a small coefficient of thermal expansion is further applied thereon. It is manufactured using a complex and diverse process that requires strict control.

These unidirectional silicon steel sheets are mainly used as iron cores for transformers and other electrical equipment, and their magnetic properties include high magnetic flux density (represented by the Se value) and iron loss (WIT/So In addition, it is required to have an insulating film with good surface quality.

Particularly in the wake of the energy crisis, demand for features that reduce power loss has increased significantly, and the need for unidirectional silicon steel sheets with lower iron loss as core materials for transformers has become increasingly important. .

Now, it is no exaggeration to say that the history of improving iron loss in grain-oriented silicon steel sheets is the history of improving the Goss-oriented secondary recrystallized texture, and as a method to control such secondary recrystallized grains. Ha, 7f! A method has been implemented in which primary recrystallized grain growth inhibitors such as N, MnS, and MnSe are used to preferentially grow Goss-oriented secondary recrystallized grains.

Recently, in addition to controlling the secondary recrystallization texture, laser irradiation on the steel sheet surface (Tasashi Tsuchiyama:
iron and rope.

69 (1983), P, 895. Tokuko Sho 57-2252
JP-A No. 57-53419, JP-A No. 58-24605, JP-A No. 5B-24606) or plasma irradiation (JP-A-62-96617, JP-A-62-151511, JP-A-62-151516 and JP-A-62-62- No. 151,517) proposes an innovative method of introducing local microstrain to subdivide magnetic domains and reduce iron loss. However, steel sheets manufactured according to these methods have the disadvantage that microstrains disappear when heated to a high temperature range, so they cannot be used as materials for wound core transformers that require high-temperature strain relief annealing.

As a method that does not cause deterioration of iron loss even if such high-temperature strain relief annealing is performed, there is a method of forming grooves or serrations on the surface of the finish annealed plate (Japanese Patent Publication No. 50-3567).
No. 9, JP-A-59-28525 and JP-A-59-1975
20), a method of forming finely recrystallized grain regions on the surface of a finish annealed plate (see JP-A-56-130454), a method of forming uneven thickness or defective regions in the forsterite coating ( JP-A No. 60-92479, No. 6
No. 0-92480, No. 60-92481 and No. 60-2
58479), a method of forming different compositional regions in the steel base, in the forsterite coating, or in the tension insulation coating (JP-A-60403124 and JP-A-60-10318)
2), etc. are known.

However, none of these methods has a small effect on reducing iron loss when the process is complicated, and the manufacturing cost is high, so at present they have not been adopted industrially. .

Regarding this point, the inventors reported in Japanese Patent Application Laid-Open No. 63-186826 that by irradiating the surface of a unidirectional silicon steel plate with an insulating film with an electron beam along the width direction of the steel plate, proposed a technology that can be applied to both stacked iron cores and wound iron cores.

(Means for solving the problem) However, in order to prevent the iron loss of the material from deteriorating even if it is subjected to high-temperature strain relief annealing as a material for wound iron core transformers, it is necessary to apply a strong electron beam to the surface of the steel sheet ( It is necessary to increase the power density and reduce the scanning interval, but in this case there is a risk of deterioration of the plate shape, and there is still room for improvement.

(Problems to be Solved by the Invention) A unidirectional silicone material in which the iron loss reduced by the subdivision of magnetic domains does not deteriorate even when subjected to strain relief annealing, and also does not cause deterioration of the plate shape. It is an object of the present invention to propose an electron beam irradiation method useful for manufacturing steel sheets.

(Means for solving the problem) In order to obtain a low iron loss unidirectional silicon steel plate with a good plate shape that can be applied to wound cores, we have conducted various experiments and studies.
Compared to electron beam irradiation (hereinafter simply referred to as EB irradiation) on one side of a steel plate, it has been found that EB irradiation on both sides of the steel plate at the same position at the same time and in the same scanning direction is extremely effective. This invention is based on the above knowledge. That is, this invention provides a unidirectional silicon steel sheet with an insulating coating film mainly composed of phosphate and colloidal silica on the surface that has been subjected to finish annealing.
In irradiating the surface of the steel plate with an electron beam over the entire length thereof, the electron beam is repeatedly irradiated with the same scanning direction along the width direction of the steel plate at the same position on the front and back surfaces of the steel plate. This is a method for producing a unidirectional silicon steel sheet whose properties do not deteriorate even when subjected to strain relief annealing.

(Function) First, the experimental results that formed the basis of this invention will be explained.

Table-1 shows C: 0.068χ, Si: 3.39Z
, Mn: 0.086χ, Al: 0.032χ
, Se: 0.028χ, Mo: 0.013%,
N: 0.0076r, Cu: 0.055K
A hot-rolled silicon steel sheet containing 1,050°C was cold-rolled twice with intermediate annealing at 1050°C to obtain a final cold-rolled sheet with a thickness of 0.20++o, and then desorbed in wet hydrogen at 840°C. After primary recrystallization annealing that also serves as charcoal, 10° from 850°C
After increasing the temperature at 10°C/hr to 1050°C at C/hr to develop Goss-oriented secondary recrystallized grains,
Magnetic properties of the steel plate when purification annealing is performed in dry H2 of C, an insulating film containing phosphate and cocoidal silica as main components is formed on the surface of the steel plate, and then EB irradiation is performed using various irradiation methods. This is the result of a survey regarding the shape.

In addition, in this experiment, the accelerating voltage of 225 KV, 1.0 m
A (D current, spacing 6IiI11, degree of vacuum 4 x 10
- Perform EB irradiation under the Torr condition, and then
Furthermore, an insulating film was applied and strain relief annealing was performed at 800°C for 3 hours.

In Table 1, the degree of improvement in iron loss is greater in Test Nos. (2) to (4), which involve double-sided irradiation, than in Test No. (1), which involves single-sided irradiation. However, when irradiating both sides of a steel plate, regarding Nα(2) (3), the angle and position of the EB scanning line with respect to the longitudinal direction of the steel plate occur on the front and back sides of the steel plate, so magnetic domain refining is insufficient. This is not done, and irregularities occur in the plate shape due to deviations in the irradiation position.

By using the same irradiation position and the same EB scanning direction, both magnetic properties and plate shape were excellent as in test Nα (4). From this experiment, compared to no EB irradiation as in test Nα (5), EB irradiation can improve iron loss even after strain relief annealing, but depending on the irradiation conditions, the method of improving iron loss and It is clear that the plate shapes are different.

Because unidirectional silicon steel sheets are functional materials,
It is essential that the product has excellent magnetic properties, but if the shape of the steel plate is poor, the space factor will decrease when assembled into a transformer, resulting in poor transformer performance. Therefore, in such a steel plate, not only the magnetic properties but also the plate shape have a significant influence on the quality of the product.

As the silicon-containing steel which is a suitable material for this invention, conventionally known compositions are suitable, and typical compositions thereof are shown below.

1) C: 0.01-0.08%, Si: 2.
5-4.0%, Mn: 0.01-0.2%, gate o:
0.003-0.1%, Sb: 0.005-0.
2%, either 0.005 to 0.5 of S and Se
%2) C: 0.01-0.1%, Si: 2.5
~4.0%, Mn: 0.01~0.2%, 8l
: 0.005 to 0.06%, N: 0.00
1-0.2%, Sn: 0.01-0.5%, C
u: 0.01-0.3%, any one of S and Se 0.005-0.5%3) C: 0.01-0.0
6%, Si: 2.5-4.0%, Mn: 0.01
~0.2%, S: 0.005~0.05%, B
:0.0003~o, oos%, N:0. O
A silicon steel material containing 1 to 0.01% O is suitable.

It is preferable to use an electron beam with a small diameter generated at high voltage and low current as the electron beam to irradiate the steel plate. Specifically, the acceleration voltage is 65KV ~ 5
It is preferable to set the accelerating current in the range of 0.001 to 5 mA in the range of 0.00 KV.

In carrying out this invention, batch processing is also possible, but from the viewpoint of cost, air-to-A processing is possible.
It is preferable to use an IR type continuous device; however, in EB irradiation, either linear or linear irradiation may be used.

(Example) Unidirectional silicon mli (C: 0.044!, Si
: 3.44X, Mn: 0.070χ, Mo:
0.014χ, Se: 0.021χ, Sb: 0
．． 025χ) and sample N, which also has a thickness of 0.23 mm.
o, 2 unidirectional silicon steel plate (C: 0.068χ,
Si: 3.42χ, A1: 0.024χ, Se:
0.020χ, Sb: 0.025χ, Mo:
The test Nα in Table 1 above was applied to approximately 6.5 tons of coils, each of which was wound with an insulating coating mainly composed of phosphate and colloidal silica.
Localized heat treatment by EB irradiation was applied to the entire length under the same conditions as in (4), and an insulating film was further applied on top of that, followed by strain relief annealing at 800"C for 15 hours. We investigated the characteristics and plate shape.

The processing conditions during EB irradiation are acceleration voltage: 225KV.
, Current: 1.2mA, Scan interval = 5 mm, Beam diameter:
The diameter of the dish was 0.12, the degree of vacuum was 5 Xl0-'mmHg, and the line speed was 10 m/min.

As a result, sample No. 1 unidirectional silicon steel sheet had B
8 is 1.91T XWI7ys. is 0.79 brightness, and B8 is 1 for the unidirectional silicon steel sheet of sample Nα2.
,94,W+tzs.

was 0.78 W/kg, and it was confirmed that the plate shape was good in all cases.

(Effects of the Invention) Thus, according to the present invention, it is possible to provide a unidirectional silicon steel plate with a good shape that does not cause deterioration of core loss even when subjected to strain relief annealing.

Claims (1)

[Claims] 1. A unidirectional silicon steel plate that has been subjected to finish annealing and has an insulating coating film mainly composed of phosphate and colloidal silica on its surface is irradiated with an electron beam over the entire length of the steel plate. An electron beam irradiation method comprising repeatedly irradiating an electron beam with the same scanning direction along the width direction of the steel plate at the same position on the front and back surfaces of the steel plate.